1. Field of the Invention
This invention relates to improvements in a weft picking control system for a fluid jet loom, and more particularly to such a weft picking control system in which response in control is improved throughout a wide region of loom operating conditions.
2. Description of the Prior Art
Hitherto a variety of weft picking control systems for an air jet loom have been proposed and put into practical use in order to achieve an appropriate weft picking. One of them is disclosed in Japanese Pat. Provisional Publication No. 59-71459 and arranged as follows: In order to accomplish a weft picking by ejecting pressurized air from a weft inserting nozzle (main nozzle) for a predetermined time, the air pressure of the pressurized air to be supplied to the weft inserting nozzle is so controlled as to regulate at a predetermined target value a weft picking condition (for example, a timing of the weft yarn reaching a counter-weft picking side) for a picked weft yarn, thereby intending achievement of an appropriate weft picking regardless of kinds of yarns for the weft yarn.
However, difficulties have been encountered in such a conventional weft picking system of the type wherein air pressure fed to the weft inserting nozzle is controlled in response to the detected weft picking condition of the picked weft yarn, in which the pressure in a surge tank disposed upstream of the weft inserting nozzle is usually controlled to prevent turbulence of air upon sudden change in air pressure, thereby degrading response in control. Additionally, with such a control, there arise the following problems: When the air pressure excessively rises, a weft tension becomes too high at the termination period of weft picking, thereby causing breakage or cutting of the weft yarn. Besides, since the air pressure has an upper limit (or original pressure in a pressurized air source), there is a possibility of air pressure control becoming impossible.